JPH0651508U - Filter clogging alarm device - Google Patents

Abstract

(57) [Summary] [Purpose] Prevents malfunctions when liquid viscosity is high and when pulsation occurs. [Structure] A pressure difference detection device 1 including pressure sensors 8 and 9, an input circuit 10 and a comparator 11 has a difference (Pa-P) between a pressure Pa on a pump 7 side and a pressure Pb on an outflow side of a filter 6.
b) is detected. The liquid temperature monitoring device 2 calculates the limit pressure difference α corresponding to the liquid temperature t measured by the thermocouple 12 by the arithmetic device 14. The comparator 11 activates the timer 17 of the alarm output device 3 when Pa−Pb> α, and resets the timer 17 when Pa−Pb ≦ α. The alarm output device 3 compares the output time C of the timer 17 with the set time D of the setter 19 in the comparator 18, and outputs an alarm to the alarm device 4 via the alarm output circuit 20 when C> D. And activate it.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for issuing a warning when the clogging of a filter provided in a liquid flow path exceeds a limit.

[0002]

[Prior art]

 As a filter clogging alarm device, a device shown in FIG. 3 is conventionally known. This filter clogging alarm device monitors the pressure difference between the pump 7 side (inflow side) and the outflow side of the filter 6 provided in the hydraulic fluid flow path (pipe line) 5 with the pressure switch 21, and When the difference exceeds the set value, the pressure switch 21 outputs an alarm signal to the alarm device 4.

[0003]

[Problems to be solved by the device]

 However, the pressure difference in the filter 6 varies greatly depending on the viscosity and pulsation of the hydraulic oil flowing in the flow path 5, so that when the oil temperature is low and the pressure difference increases, the pulsation causes a momentary pressure difference. Even if the difference becomes large, there is a problem that an alarm is issued regardless of the degree of clogging of the filter 6.

An object of the present invention is to provide a clogging alarm device for a filter, which always gives a correct alarm without being affected by the liquid temperature which may be low or may cause pulsation. .

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a pressure difference detection device for detecting a pressure difference between the liquid on the inflow side and the liquid on the outflow side of a filter provided in a liquid flow path, and a liquid flowing in the liquid flow path. The liquid temperature monitoring device that detects the temperature of the liquid and calculates the limit pressure difference at that temperature, and the pressure difference of the liquid detected by the pressure difference detection device is larger than the limit pressure difference that is calculated by the liquid temperature monitoring device. The configuration is provided with an alarm output device that outputs an alarm signal when the state continues for a set time or longer, and an alarm device that operates in response to the alarm signal of this alarm output device.

[0006]

[Action]

 The liquid temperature monitoring device determines the critical pressure difference corresponding to the temperature of the liquid flowing through the liquid flow path. The alarm output device also sends an alarm signal when the liquid pressure difference detected by the pressure difference detection device is larger than the limit pressure difference calculated by the liquid temperature monitoring device for a set time or longer. Output to. Therefore, even if the liquid temperature is low and the pressure difference becomes large, or even if the pulsation causes the pressure difference to increase momentarily, the alarm device will not issue an alarm unless the degree of filter clogging becomes large. .

[0007]

【Example】

 FIG. 1 shows an embodiment of the present invention. The filter clogging alarm device according to the present invention includes a pressure difference detection device 1, a liquid temperature monitoring device 2, an alarm output device 3, and an alarm device 4. The pressure difference detection device 1 includes a pressure sensor 8 for detecting a pressure Pa on the pump 7 side (inflow side) of a filter 6 provided in the liquid flow path 5, a pressure sensor 9 for detecting a pressure Pb on the outflow side, It is composed of an input circuit 10 of both pressure sensors 8 and 9 and a comparator 11 for comparing the two pressures Pa and Pb, and detects the pressure difference (Pa-Pb) between the inflow side and the outflow side of the filter 6.

The liquid temperature monitoring device 2 includes a thermocouple 12, a thermocouple input circuit 13, and a computing device 14. The thermocouple 12 detects the temperature of the liquid in the tank 16 flowing through the liquid flow path 5, and outputs the detected temperature to the arithmetic unit 14 via the thermocouple input circuit 13. The computing device 14 obtains the viscosity Y of the liquid, which is a function thereof, from the liquid temperature t (° C.), and also determines the limit pressure difference α corresponding to the viscosity Y. The limit pressure difference α is a limit value of the allowable range of the liquid pressure difference (Pa−Pb) in the viscosity Y of the liquid at that time, and is output to the comparator 11 of the pressure difference detection device 1.

The alarm output device 3 includes a timer 17, a comparator 18, a time setting device 19, and an alarm output circuit 20. The timer 17 is connected to the comparator 11 of the pressure difference detection device 1, and is reset when the pressure difference (Pa−Pb) of the liquid detected by the pressure difference detection device 1 is less than or equal to the limit pressure difference α. When the difference (Pa−Pb) is larger than the limit pressure difference α, the time is counted and output to the comparator 18. The comparator 18 compares the time D set in the time setter 19 with the output time C of the timer 17, and when the output time C of the timer 17 exceeds the set time D, the alarm output circuit 20 is used. An alarm signal is output to the alarm device 4.

The alarm device 4 is composed of a lamp, a buzzer, etc., and operates when an alarm signal is output from the alarm output circuit 20 to inform that the filter 6 has reached the limit of clogging.

Next, the operation of the filter clogging warning device according to the present invention constructed as described above will be described with reference to the flowchart of FIG. The liquid such as hydraulic oil sent from the pump 7 to the liquid flow path 5 is supplied to an operating device (not shown) such as a hydraulic cylinder or hydraulic motor through the filter 6. At this time, the pressure difference detection device 1 individually measures the pressure Pa on the inflow side and the pressure Pb on the outflow side of the filter 6 by the pressure sensors 8 and 9, and detects the pressure difference (Pa-Pb).

On the other hand, the liquid temperature monitoring device 2 detects the temperature t of the liquid in the tank 16 flowing through the liquid flow path 5 by the thermocouple 12 (S1), and the limit pressure difference α corresponding to the liquid temperature t. Is calculated (S2). The comparator 11 of the pressure difference detection device 1 determines whether the liquid pressure difference (Pa-Pb) is larger than the limit pressure difference α (S3), and when it is larger (Pa-Pb> α), activates the timer 17 ( S4), and if Pa-Pb≤α, the timer 17 is reset (S5).

When the liquid pressure difference (Pa−Pb) is larger than the limit pressure difference α and the timer 17 is activated, the comparator 18 of the alarm output device 3 causes the output time C of the timer 17 and the time setter 19 to operate. The set time D is compared (S6), and when the output time C of the timer 17 exceeds the set time D, an alarm is output to the alarm device 4 via the alarm output circuit 20 (S7), and an alarm is issued. Operate vessel 4. When the timer 17 is reset and when C ≦ D, the process returns to the start. Since the pressure increase due to pulsation is instantaneous, the set time D is set in the time setting device 19 to prevent this malfunction. That is, when the clogging alarm is released within the set time D, it is regarded as a pulsation alarm and the alarm is not generated.

[0014]

[Effect of device]

 As described above, the filter clogging alarm device according to the present invention includes a pressure difference detection device for detecting a pressure difference between the liquid on the inflow side and the liquid on the outflow side of the filter provided in the liquid flow path, and the liquid flow path. The liquid temperature monitoring device that detects the temperature of the liquid flowing through it to determine the limit pressure difference at that temperature, and the liquid pressure difference detected by the above-mentioned pressure difference detection device is the limit pressure difference that was calculated by the above liquid temperature monitoring device. The alarm output device that outputs an alarm signal when a condition larger than the above continues for a set time or more, and an alarm device that operates by receiving the alarm signal of this alarm output device are configured. Even if the temperature is low and the viscosity is high, or if pulsation occurs, it does not malfunction, and it has the advantage that a correct alarm is always issued only when the filter has reached the limit of clogging.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a filter clogging warning device according to the present invention.

FIG. 2 is a flowchart of the present device.

FIG. 3 is a block diagram of a conventional filter clogging alarm device.

[Explanation of symbols]

 1 Pressure difference detection device 2 Liquid temperature monitoring device 3 Alarm output device 4 Alarm device 5 Liquid flow path 6 Filter

Claims (1)

[Scope of utility model registration request] 1. A pressure difference detection device for detecting a pressure difference between liquid on the inflow side and liquid on the outflow side of a filter provided in a liquid flow path,
A liquid temperature monitoring device that detects the temperature of the liquid flowing through the liquid flow path and calculates a limit pressure difference at that temperature, and a liquid pressure difference detected by the pressure difference detection device is calculated by the liquid temperature monitoring device. A filter provided with an alarm output device that outputs an alarm signal when a state larger than the limit pressure difference continues for a set time or longer, and an alarm device that operates by receiving an alarm signal from the alarm output device. Clogging alarm device.